Exhaust gas recirculation is a technique employed in many of the engines operated today. Exhaust gas recirculation reduces the amount of contaminants released by the exhaust gas by reducing the oxygen concentration in the intake manifold; and, thereby reducing adverse chemical reactions during combustion which produce contaminants. An exhaust gas recirculation conduit commonly has an inlet attached to the exhaust manifold of an internal combustion engine and an outlet attached to the intake manifold. Different methods are utilized to control the amount of flow through the exhaust gas recirculation line. For example, a control valve may be placed on the line to control how much flow travels through the line. In addition, a cooler is commonly used to recool the air before it is placed back in the intake manifold for combustion.
A common method for controlling the flow rate of exhaust gas through the exhaust gas recirculation line is to use an exhaust throttle to create backpressure to drive the exhaust through the exhaust gas recirculation line. One problem with this method is that an exhaust throttle is expensive. In addition, a variable geometry turbocharger may be used to drive exhaust flow through the exhaust gas recirculation line. This option is also more expensive relative to fixed geometry or wastegate turbochargers.
More cost effective solutions for EGR (exhaust gas recirculation) are desired.